8 sec here in Colorado. Splains why I am always getting lower seating assignments on Southwest... otherwise, doesn't bother me a bit. 
I'm kind of a watch geek and noticed that AT&T's time displayed on my iPhone is about 00:01:40 (1 min 40 secs) behind my atomic watch. You can verify this your self at the time.gov web site. My Verizon phone was almost spot on. I don't know if this varies area to area or if it is nation wide. No big deal but made me go hmmm.
Los Angeles about 1:12 behind
Just checked mine in downtown Boston, MA.
My iPhone is 3 seconds behind.![]()